This research is concerned primarily with understanding what constitutes electrodermal response conditioning and what, in the context of various controls, constitutes its properties. Particular emphasis is being placed on differences between first- and second-interval responding. These response intervals are intervals which include, respectively, orienting responses and responses which are not signal- onset elicited but which are anticipatory to the occurrence of a mildly noxious stimulus. Arrangements of various stimulus-stimulus and stimulus-time contingencies will be made, interactions of conditioned stimulus and unconditioned stimulus intensities will be studied, and the relationship of on-trial and off-trial responding will be examined as a function of various independent variable manipulations.